Mobile communications systems have been widely used in the past few decades. Pluralities of cellular communication servers are deployed in populated regions around the world, and thus provide a global communication network. However, such cellular communication systems are limited to regions where suitable servers and antennas are deployed.
In various situations, reliable communication is required even at remote locations where no cellular antennas are present at a distance which would enable reception. Telephonic communication through satellites allows a user to be located almost at any corner of the globe while being available for incoming calls, or capable of making outgoing calls. Current commercially available mobile satellite phones utilize communication through dedicated low-orbit satellites allowing global coverage and efficient communication with low gain transmission systems.
Well known is the Iridium Inc. satellite communication system which utilizes 66 active satellite units, as well as additional “spare” units for use in case of failure of one or more of the active satellites. The satellites are located in low orbit to allow communication with handheld mobile devices of relatively small dimensions. The Iridium communication system utilizes several additional inactive satellites located in orbit. These satellites are used as spares to provide coverage in case of failure of one or more of the active satellites.
Other satellite phone devices require high gain antennas for reliable communication through satellites in orbit. For example, U.S. Pat. No. 6,023,242 describes an Earth station having an antenna configured to establish communication with a satellite. The Earth station stores a table of satellite position data for a plurality of satellites and is configurable to enable its own location position on the surface of the Earth as well as the azimuth and elevation of its antenna to be obtained. The tabulated satellite position data is then utilized to calculate the position of the satellite in relation to the location position. Thereafter at least one of the satellites is selected with which to establish communication and in response to the selection and the obtained azimuth and elevation, a direction is determined in which to configure the antenna for operation with the at least one selected satellite. Following determination of the direction, the antenna is configured for operation with the at least one selected satellite. The location position and the azimuth and elevation of the antenna may be determined through the Earth station comprising a GPS receiver. The Earth station may be configured as a mobile, portable or fixed unit and the invention is configurable to enable communication to be established with geostationary satellites, non-geostationary satellites or a combination of both geostationary and non-geostationary satellites.